blue green algae surrounding a boat in the water

Blue-Green Algae

Blue-green algae, technically known as cyanobacteria, are microscopic organisms that are naturally present in lakes and streams. They usually are present in low numbers. Blue-green algae can become very abundant in warm, shallow, undisturbed surface water that receives a lot of sunlight. When this occurs, they can form blooms that discolor the water or produce floating rafts or scums on the surface of the water.

Learn more from the NYS Dept of Health